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-   -   Invicisd compressible flow over cylinder 2D (http://www.cfd-online.com/Forums/fluent/109974-invicisd-compressible-flow-over-cylinder-2d.html)

wesam December 1, 2012 18:47

Invicisd compressible flow over cylinder 2D
 
5 Attachment(s)
hi

i have a problem in negative values of CD.

Images are shown for the solution process.

Please see the pic.

thank you

-mAx- December 4, 2012 03:12

your solution isn't converged (your second picture can prove it, since it is still oscillating)
disable the "check convergence" at 1e-3 and let iterate.
Just break the iterations once your cd has a constat value

wesam December 4, 2012 13:52

4 Attachment(s)
HI MAX

i have done what you said to me.but the result of CD is negative and it is impossible it must be positive.(aerodynamic basic).

where is the error.
thank you Mr.MAX

-mAx- December 5, 2012 01:12

I don't know...
check if the velocity and pressure distribution are ok
Check also the forces on your 2d-cylinder and compute manually your Cd
And also check if your axis are well defined, especially the one for Cd should be in same direction as fluid is flowing (it is the only explanation for negative value, since others are positive)

wesam December 10, 2012 18:39

thank you MAX

please check your e_mail.

I am in trouble
you only one can help me.

thank you

-mAx- December 11, 2012 01:31

Quote:

Originally Posted by wesam (Post 396795)
thank you MAX

please check your e_mail.

I am in trouble
you only one can help me.

thank you

did you post a thread? :rolleyes:
I don't have any email


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